Enigmatic large-toothed Campanian polycotylid plesiosaurs with specific dietary preferences and potentially wide distribution
Bibliographic record
Abstract
Most polycotylid plesiosaurians have isodont dentition with relatively small and slender conical teeth. However, large and robust caniniform teeth are known for some of their basal late Albian and early Cenomanian representatives, implying greater ecological diversity early in the evolutionary history of the clade. Here we report the first evidence of polycotylids with large teeth in the Campanian, thus c. 15 Myr younger than previous records. Several teeth with crowns exceeding 40 mm in height and some reaching 25 mm in basal diameter were collected from two Campanian localities in European Russia. These are the largest polycotylid teeth reported from the Cretaceous of Eurasia. Their large size and specific enamel ornamentation markedly differ from other known polycotylid teeth, suggesting that these teeth belong to an undescribed taxon. However, similar enamel ornamentation was previously reported for the now forgotten ‘ Piratosaurus plicatus ’ Leidy, 1865 from the Upper Cretaceous of Canada, which may indicate the wide distribution of polycotylids with such teeth in the latest Cretaceous. Unlike classical polycotylids, the new teeth have strong apical wear which implies consumption of abrasive prey, similar to modern killer whales that feed on sharks. Thus, our finding reveals higher ecological diversity of polycotylids in the latest Cretaceous, suggesting the coexistence of small-to medium-toothed and large-toothed (probably ‘latirostrine’) taxa at different times of the evolutionary history of the Polycotylidae.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".